Configure distributed publish/subscribe networks

Queue managers that are connected together into a distributed publish/subscribe topology share a common federated topic space. Subscriptions created on one queue manager can receive messages published by an application connected to another queue manager in the topology.

We can control the extent of topic spaces created by connecting queue managers together in clusters or hierarchies. In a publish/subscribe cluster, a topic object must be 'clustered' for each branch of the topic space that is to span the cluster. In a hierarchy, each queue manager must be configured to identify its 'parent' in the hierarchy.

We can further control the flow of publications and subscriptions within the topology by choosing whether each publication and subscription is either local or global. Local publications and subscriptions are not propagated beyond the queue manager to which the publisher or subscriber is connected.

• Configure a publish/subscribe cluster
  Define a topic on a queue manager. To make the topic a cluster topic, set the CLUSTER property. To choose the routing to use for publications and subscriptions for this topic, set the CLROUTE property.
• Moving a cluster topic definition to a different queue manager
  For either topic host routed or direct routed clusters, you might need to move a cluster topic definition when decommissioning a queue manager, or because a cluster queue manager has failed or is unavailable for a significant period of time.
• Adding extra topic hosts to a topic host routed cluster
  In a topic host routed publish/subscribe cluster, multiple queue managers can be used to route publications to subscriptions by defining the same clustered topic object on those queue managers. This can be used to improve availability and workload balancing. When you add an extra topic host for the same cluster topic object, we can use the PUB parameter to control when publications begin to be routed through the new topic host.
• Combining publication and subscription scopes
  From IBM WebSphere MQ Version 7.0 onwards, publication and subscription scope work independently to determine the flow of publications between queue managers.
• Combining topic spaces in publish/subscribe networks
  Combine the topic space of a queue manager with other queue managers in a publish/subscribe cluster or hierarchy. Combine publish/subscribe clusters, and publish/subscribe clusters with hierarchies.
• Connect a queue manager to a publish/subscribe hierarchy
  You connect the child queue manager to the parent queue manager in the hierarchy. If the child queue manager is already a member of another hierarchy or cluster, then this connection joins the hierarchies together, or joins the cluster to the hierarchy.
• Disconnect a queue manager from a publish/subscribe hierarchy
  Disconnect a child queue manager from a parent queue manager in a publish/subscribe hierarchy.

Parent topic: Configure publish/subscribe messaging

Related information

• Distributed publish/subscribe networks
• Publication scope
• Subscription scope
• Topic spaces
• Defining cluster topics